The invention relates to improvements in cutting or subdividing apparatus which employ replaceable cutting implements (hereinafter called knives for short). More particularly, the invention relates to methods of and to apparatus for replacing worn, otherwise damaged and/or improperly selected knives which are utilized to sever or subdivide partly finished (intermediate) products of the tobacco processing industry. Examples of such intermediate products are continuous cigarette, cigar, cigarillo or other tobacco-containing rods and continuous rods containing fillers of filter material for tobacco smoke, tubes and other products which must be severed to respectively yield plain cigarettes, filter mouthpieces or other products of unit length or multiple unit length.
A cigarette making machine is designed to turn out at least one continuous rod-like product wherein a tubular wrapper of cigarette paper surrounds a rod-like filler of shredded and/or otherwise comminuted tobacco leaves and/or other smokable material. The apparatus (known as cutoff) which is utilized to subdivide the continuous rod-like product into a file of discrete cigarettes of desired length comprises one or more knives which severs or sever the rod-like product while advancing at the speed and in the direction of movement of the rod as well as sideways across the path for the rod.
The quality of cuts across a continuously advancing cigarette rod is of considerable importance to the ultimate user because at least one end of the finished cigarette is visible. Therefore, the cutting edge(s) of the knife or knives which is or which are used to subdivide a cigarette rod is or are continuously sharpened whenever the cutoff is in use. This results in pronounced wear upon the knives, and such wear develops in addition to that which is attributable to sliding movement relative to the advancing rod in actual use of the cigarette maker. It is to be borne in mind that, in a modern cigarette making machine (e.g., that known as PROTOS 2 and distributed by the assignee of the present application), a knife must carry out several thousand cuts per minute. The wear upon the knives is so pronounced that the cutoff must receive a new knife every eight hours or so.
At the present time, the removal of used knives and their replacement with fresh (new) knives are carried out by the attendants in the cigarette making plant. This is a time-consuming operation, especially in a plant wherein several hundred machines are employed to simultaneously turn out huge quantities of plain cigarettes of desired length. The situation is analogous in numerous plants which turn out continuous filter rods, continuous tubes intended to be subdivided into shorter tubes for use in certain types of smokers' products, cigarillo rods and many other rod-shaped intermediate (i.e., semifinished) products.